X-ray phase contrast mammography has the potential to improve the diagnostic value of X-ray mammograms considerably. One special problem with phase-contrast imaging is the so-called phase wrapping problem. For instance, in the measurement setup with a Talbot interferometer with a pitch of p1 for the phase grating, phase information can be retrieved unambiguously only if the gradient of the phase front is less than 2 π/p1. This is typically achievable for a few cm of soft-tissue of constant thickness. However, this is typically not the case at the rim of the object to be imaged (object of interest), where a strong jump of the complex refraction index is present due to the tissue-air interface. This may prevent a proper phase retrieval at the rim of the breast and may hamper thus proper diagnosis at the lateral rim of the breast. Consequently, tomography or tomosynthesis may become difficult, if not impossible.